Tips for Gameplay
I've found these strategies help to increase your chances of staying in the game:
Always take out the troop landing craft first. These can be identified as the smaller and faster of the 2 type's of landing craft. The other larger one contains a troop vehicle. Either will blow-up with 2 hits from a missile or rocket. If they are the only enemy craft attacking and are spawning further from the beach save your explosive ammo and take them out with your 50 cal. They will blow-up after 2-3 seconds of continuing fire.
Next targets to acquire ASAP are the Troop Helicopters (they are the larger of the 3 types). Go for the ones that land on the left side of your screen and get them before they land or while landing otherwise they will land behind the Locomotive and be hidden.
Just as critical to shoot down quickly are the Jets. They are easiest to take out while they are just approaching you. Usually 1 Missile will take them out from a frontal assault, but if they go over your position wait until they're flying away before firing another missile otherwise it wont lock-on.
If you have a large group of foot soldiers approaching take them out with a Missile. It will destroy more than a Rocket.
The large Hoover Craft will off-load Tanks and Troop Vehicles. They will blow-up with 2 rocket hits and %0 cal fire.
In Arcade Mode at the start of a new level if you pause the game and select "Retry" it will Spawn the Landing Craft in different locations. Sometimes it's easier to dispatch the LC's if they're closer together or farther away.